In an observational study, glycosylated hemoglobin between 8% and 9% was best.

Experienced clinicians have long recognized that tight glycemic control can be perilous in frail older patients with type 2 diabetes. Now, an observational study addresses that concern. Researchers in San Francisco studied 367 community-dwelling, older patients (mean age, 80) with diabetes who participated in a comprehensive adult day-care program and were unable to live independently. Glycosylated hemoglobin (HbA1c) levels were measured at baseline, and functional decline and death were tracked during 2 years of follow-up (during which, average HbA1c levels didn't change much).

Analyses were adjusted for potentially confounding variables. Compared with patients in the reference category (HbA1c levels, 7%–8%), patients whose HbA1c levels were between 8% and 9% had a significantly lower incidence of functional decline or death (relative risk, 0.88), and those with HbA1c levels <7% had a nearly significant higher incidence of functional decline or death. Overall, the relation between HbA1c level and functional decline or death was somewhat U-shaped, with the best outcomes among patients in the 8% to 9% range. These basic patterns were noted both among patients who took only oral antidiabetic drugs and those who took insulin.

Comment: This observational study is subject to residual confounding, but it suggests that an HbA1c target in the 8% to 9% range is reasonable for older patients with diabetes who are unable to live independently. The findings support a recent guideline in which less-tight glycemic control is acceptable in older adults with long-standing diabetes (JW Gen Med Jul 24 2012).